Synthesis of Hyperbranched Polyisobutylenes by Inimer-Type Living Polymerization. 1. Investigation of the Effect of Reaction Conditions
Bibliographic record
Abstract
Hyperbranched polyisobutylenes (PIBs) have been synthesized by carbocationic copolymerization of an inimer ( ini tiator-mono mer, IM ) and isobutylene (IB). The IM used was 4-(2-methoxyisopropyl)styrene ( p -methoxycumylstyrene, pMeOCumSt), in conjunction with TiCl 4 as a co-initiator in methylcyclohexane (MeCHx)/methyl chloride (MeCl) 60/40 v/v solvent mixture at −80 °C, in the presence of 2,6-di- tert -butylpyridine (D t BP) as a proton trap. The effect of reaction conditions on the molecular weights (MW), molecular weight distributions (MWD), and branching frequencies (BR) was investigated. Hyperbranched PIBs with MWs up to M n ≈ 8 × 10 5 g mol -1 and MWD as low as 1.2 were obtained within 15−60 min reaction time, where under the same conditions the 2-chloro-2,4,4-trimethylpentane (TMPCl) monofunctional initiator would have yielded MWs in the range of M n ≈ 10 4 g/mol. BRs were determined by selective destruction of the branching points (links) and taking the ratio of the MWs before and after link destruction. The experimental BR values, ranging from 3 to 57, agreed reasonably well with values calculated using the formula BR = ( M n / M n(theo) ) − 1, where M n is the total MW of the hyperbranched PIB, and M n(theo) would be the MW if the IM would act as initiator only. The process was scaled up to 400 g of PIB/batch, sufficient for meaningful physical characterization.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".